Researchers have pinpointed the environmental source of fungal infections that have been sickening HIV/Aids patients in Southern California for decades. It literally grows on trees.
Life-threatening infections
The
discovery is based on the science project of a 13-year-old girl, who
spent the summer gathering soil and tree samples from areas around Los
Angeles hardest hit by infections of the fungus named Cryptococcus
gattii (CRIP-to-cock-us GAT-ee-eye).
Cryptococcus, which
encompasses a number of species including C. gattii, causes
life-threatening infections of the lungs and brain and is responsible
for one third of all Aids-related deaths.
The
study, which appears in PLOS Pathogens, found strong genetic evidence
that three tree species – Canary Island pine, Pohutukawa and American
sweetgum – can serve as environmental hosts and sources of these human
infections.
"Just as people who travel to South America are told
to be careful about drinking the water, people who visit other areas
like California, the Pacific Northwest and Oregon need to be aware that
they are at risk for developing a fungal infection, especially if their
immune system is compromised," said Deborah J. Springer, Ph.D., lead
study author and postdoctoral fellow in the Centre for Microbial
Pathogenesis at Duke University School of Medicine.
In search of fungi
A
few years ago, Duke's chairman of Molecular Genetics and Microbiology,
Joseph Heitman M.D., was contacted by longtime collaborator and UCLA
infectious disease specialist Scott Filler, M.D., whose daughter Elan
was looking for a project to work on during her summer break. They
decided it would be fun to send her out in search of fungi living in the
greater Los Angeles area.
Read: No fun in fungus
The
student sampled 109 swabs of more than 30 tree species and 58 soil
samples, grew and isolated the Cryptococcus fungus, and then sent those
specimens to Springer at Duke. Springer DNA-sequenced the samples from
California and compared the sequences to those obtained from HIV/Aids
patients with C. gattii infections.
She was surprised to find that
specimens from three of the tree species were genetically almost
indistinguishable from the patient specimens.
The researchers also
found that the C. gattii isolated from the environment were fertile,
reproducing either by sexual or asexual reproduction.
"That
finding is important for long-term prevalence in the environment,
because this fungal pathogen will be able to grow, reproduce, disperse
spores, and serve as a source of ongoing infections," Springer said.
Image: Foot fungus disease from Shutterstock
Source: http://www.health24.com/Medical/HIV-AIDS/News/Fungus-deadly-to-Aids-patients-grows-on-trees-20140822
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